When should low hydrogen electrodes be baked before use?

Low hydrogen electrodes are specifically designed to reduce the risk of hydrogen embrittlement in welded joints by minimizing the amount of hydrogen introduced into the weld. These electrodes can absorb moisture from the environment, which is a critical factor that can lead to the formation of hydrogen during the welding process.

Baking low hydrogen electrodes is an essential practice to ensure their effectiveness. The primary reason for baking is to drive out any moisture that may have been absorbed. This is necessary when they have been exposed to air for longer than the specified time indicated in various guidelines, such as Table 5.1, which likely outlines limits for exposure to environmental conditions.

When low hydrogen electrodes are exposed to moisture or air for a duration exceeding the recommended guidelines, the risk of hydrogen being introduced into the weld increases. Baking the electrodes prior to use removes excess moisture, thus maintaining their integrity and performance.

In summary, low hydrogen electrodes should be baked when they have been exposed to air beyond the allowable time, as outlined in the relevant guidelines, to ensure optimal welding results and minimize the potential for hydrogen-related defects in the welds.